I hope someone can help me . I have

[bryan gallon]

I hope someone can help me . I have a Bosch rexroth proportional valve and I need to zero the main spool as I have cylinder drift . What do the little pots (screws) do behind the black caps thanks

 

[FluidPowerUser]

What’s the part number for the valve?

The screws are most likely offset, ramp, gain or max current.

With the product details known, I can give you more details.

 

[bryan gallon]

hope this helps I didn’t know if they were span dither gain etc like on external amplifier cards I tried to download pdf from Bosch but not much help

 

[TugboatEng]

There does not appear to be any physical adjustment meaning you'll need to adjust the zero in your controller or fix the leaking cylinder piston.

 

[FluidPowerUser]

There is no adjustment for this valve. As stated, you will need to reset the Imin value to keep the spool in the neutral position.

If the cylinder is still moving with the Imin set below the deadband of the valve, it's because there is excess leakage across the spool.